Tour guides Gerald Pereira and Oscar Solano Rojas were conducting the “Sloth Tour” for the Sloth Conservation Foundation early on the morning of December 20th last year, when they saw something that stopped them dead in their tracks. Tucked into the leaves of a Cecropia (Guarumo in Spanish) tree was a mama sloth tending to a baby sloth, but the two sloths were from totally different species. Mama sloth was a 3-toed and baby was a 2-toed. This is only the third time such a pair has been documented anywhere.

Said Oscar Solano, “I had already saw the two species in the same tree many times, and at first we thought it was just a coincidence that they were together. When we found them it seemed like they were just waking up. They both started scratching, and then the baby separated from the female, fed on Cecropia leaves a little, and I thought that was the end of the interaction.” But then the baby sloth returned to the adult, who cuddled the baby to her chest as if it were her own.

The guides took another tour to the same spot the next day, and found the same sloths interacting just like a mother and her baby. The 3-toed had adopted the 2-toed, an “interspecies adoption”, one of only three documented instances among sloths. Founder of the Sloth Conservation Foundation Dr. Rebecca Cliffe commented on this highly unusual incident, “This is the first time that anything like this has ever been seen before in wild sloths, and it is certainly very interesting. I am used to sloths surprising us, but this has to be one of the most unusual things I have heard about. I suspect there are three possible scenarios which may have led to this happening.”

1. Accidental Human Interference. Someone found the cub alone, and tried to reunite it with the closest sloth around, not realizing they were from totally different species.
2. The baby sloth lost its real mother, and clung to the fur of the closest sloth around. Usually, a 3-toed sloth would reject a 2-toed baby.
3. The baby lost its mama at approximately the same time as the adult lost a baby of its own. A bond was formed naturally due to a mixture of instincts and hormones. Dr. Cliffe thinks this is the most likey scenario, bizarre as it might be.

In Costa Rica there are two different species of sloths, the Hoffman’s two-toed sloth (Choloepus Hoffmani), and the Brown-throated three-toed sloth (Bradypus Variegatus). The difference is actually the number of fingers of each, not the number of toes, since all sloths have three toes. Two-toed sloths are noticeably bigger than three-toed, and their diets are different. It was thought that the baby sloth was found at about seven months of age, and probably already weaned. The characteristic that all sloths share is specialized hair that encourages algae growth, giving them a green tinge that helps them camouflage in the trees.
In addition to green algae, sloth hair provides a home to an entire ecosystem of invertebrates, some species of which are found nowhere else on earth. Their fur can host up to 950 moths and beetles at a time.

Mama sloth seems to have just added one more critter to her brood

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